The present invention relates generally to improvements in devices and machines for handling and treating work pieces and it relates particularly to an improved vacuum chuck device.
In many manufacturing processes such as in the spinning of wafers, masks and microelectrical substrates, for example in the application of coating materials to a substrate, typically a thin wafer, it is often necessary to retain the work piece, for example the thin wafer, on a rotating chuck. It is a common procedure where the work piece is of a fragile or delicate nature and where the work piece should be rapidly secured to or separated from the chuck that a vacuum chuck is employed, that is, a chuck in which suction is applied to the rear face of the work piece and the work piece is retained on the chuck under the influence of the atmospheric or ambient pressure. The chuck is accordingly connected to a vacuum pump or tank by way of a hollow motor drive shaft on which the chuck is mounted. To this end, the shaft bore is connected by way of a rotatable pneumatic coupling to the vacuum source. The rotatable couplings heretofore employed possess many drawbacks and disadvantages. They are unreliable, awkward, introduce variations in smoothness, and inefficient devices which are frequently short lived, bulky and expensive and subject to leakage and are of little versatility and otherwise leave much to be desired.